Terahertz element and semiconductor device

ABSTRACT

A terahertz element of an aspect of the present disclosure includes a semiconductor substrate, first and second conductive layers, and an active element. The first and second conductive layers are on the substrate and mutually insulated. The active element is on the substrate and electrically connected to the first and second conductive layers. The first conductive layer includes a first antenna part extending along a first direction, a first capacitor part offset from the active element in a second direction as viewed in a thickness direction of the substrate, and a first conductive part connected to the first capacitor part. The second direction is perpendicular to the thickness direction and first direction. The second conductive layer includes a second capacitor part, stacked over and insulated from the first capacitor part. The substrate includes a part exposed from the first and second capacitor parts. The first conductive part has a portion spaced apart from the first antenna part in the second direction with the exposed part therebetween as viewed in the thickness direction.

TECHNICAL FIELD

The present disclosure relates to terahertz elements and semiconductordevices.

BACKGROUND ART

In recent years, as electronic devices such as transistors areminiaturized and their sizes are reduced to nano-scale, a new phenomenoncalled quantum effect has been observed. Studies are being made todevelop an ultra-high speed device or a new function device utilizingthe quantum effect. In particular, attempts are being made to utilizethe frequency range of 0.1 to 10 THz, called a terahertz band, toperform high-capacity communication or information processing, imagingand measurement, for example. This frequency region is an undevelopedregion between light and radio waves, and a device that operates in thisfrequency band, if realized, could be used for many applications such asimaging and high-capacity communication or information processingdescribed above, as well as measurement in various fields such asphysical properties, astronomy or biology.

SUMMARY OF THE INVENTION

According to a first aspect of the present disclosure, a terahertzelement is provided. The terahertz element includes a semiconductorsubstrate, a first conductive layer, a second conductive layer and anactive element. The first conductive layer and the second conductivelayer each are formed on the semiconductor substrate and insulated fromeach other. The active element is formed on the semiconductor substrateand electrically connected to the first conductive layer and the secondconductive layer. The first conductive layer includes a first antennapart extending along a first direction, a first capacitor partpositioned offset from the active element in a second direction asviewed in a thickness direction of the semiconductor substrate, and afirst conductive part connected to the first capacitor part. The seconddirection is perpendicular to the thickness direction and the firstdirection. The second conductive layer includes a second capacitor part.The second capacitor part is stacked over the first capacitor part whilebeing insulated from the first capacitor part. The semiconductorsubstrate includes an exposed part that is exposed from the firstcapacitor part and the second capacitor part. The first conductive parthas a portion that is spaced apart from the first antenna part in thesecond direct ion with the exposed part therebetween as viewed in thethickness direction.

According to a second aspect of the present disclosure, a semiconductordevice is provided. The semiconductor device includes a support, aterahertz element provided by the first aspect and disposed on thesupport, and an insulating part disposed on the support. The insulatingpart is formed with an opening in which the terahertz element is housed.The opening has a first side surface. The first side surface is inclinedwith respect to a thickness direction of the support.

The description that “an object A is formed on an object B” and “anobject A is formed above an object B” includes, unless otherwisesuggested, “the object A is formed directly on the object B” and “theobject A is formed on the object B with another object interposedbetween the object A and the object B”. Similarly, the description that“an object A is disposed on an object B” and “an object A is disposedabove an object B” includes, unless otherwise suggested, “the object Ais disposed directly on the object B” and “the object A is disposed onthe object B with another object interposed between the object A and theobject B”. Similarly, the description that “an object A is stacked on anobject B” and “an object A is stacked over an object B” includes, unlessotherwise suggested, “the object A is stacked directly on the object B”and “the object A is stacked on the object B with another objectinterposed between the object A and the object B”.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a semiconductor device according to afirst embodiment;

FIG. 2 is a plan view of a terahertz element of the first embodiment;

FIG. 3 is a view obtained by omitting a first conductive part and afirst capacitor part from FIG. 2;

FIG. 4 is a view showing a region IV in FIG. 2 as enlarged;

FIG. 5 is a sectional view showing details of an active element of thefirst embodiment;

FIG. 6 is a view showing a part of FIG. 5 as enlarged;

FIG. 7 is a sectional view taken along line VII-VII in FIG. 2;

FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 2;

FIG. 9 is a sectional view taken along line IX-IX in FIG. 2;

FIG. 10 is a sectional view taken along line IX-IX in FIG. 2;

FIG. 11 is a sectional view taken along line XI-XI in FIG. 2;

FIG. 12 is a sectional view taken along line XII-XII in FIG. 2;

FIG. 13 is a sectional view taken along line XIII-XIII in FIG. 2;

FIG. 14 is a sectional view taken along line XIV-XIV in FIG. 2;

FIG. 15 is a sectional view taken along line XV-XV in FIG. 2;

FIG. 16 is a sectional view of the semiconductor device of FIG. 1;

FIG. 17 is a plan view showing a variation of the terahertz element;

FIG. 18 is a plan view of a terahertz element of a second embodiment;

FIG. 19 is a plan view of a terahertz element of a third embodiment;

FIG. 20 is a plan view of a terahertz element of a fourth embodiment;

FIG. 21 is a perspective view of a semiconductor device as an example;

FIG. 22 is a sectional enlarged view showing a part of a semiconductordevice as an example;

FIG. 23 is a graph showing the antenna gain versus frequencies ofterahertz waves for different inner diameters;

FIG. 24 is a graph showing the antenna gain versus frequencies ofterahertz waves for different dimensions; and

FIG. 25 is a graph showing the antenna gain versus frequencies ofterahertz waves for different dimensions.

MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present disclosure are described below withreference to the accompanying drawings.

First Embodiment

A first embodiment of the present disclosure is described below withreference to FIGS. 1-17. FIG. 1 is a perspective view of a semiconductordevice according to a first embodiment.

The semiconductor device A1 shown in the figure is a terahertz radiator.The semiconductor device A1 includes a terahertz element B1, a support(including a wiring board 81), an insulating part 85 and wires 871, 872.

FIG. 2 is a plan view of the terahertz element of the first embodiment.

The terahertz element B1 shown in the figure is an element configured toradiate high-frequency electromagnetic waves with frequencies in theterahertz band. The terahertz element B1 includes a semiconductorsubstrate 1, a first electrically conductive layer 2, a secondelectrically conductive layer 3, an insulating layer 4 (shown in FIG.7), and an active element 5.

The semiconductor substrate 1 is made of a semiconductor and issemi-insulating. The semiconductor forming the semiconductor substrate 1is InP, for example. The semiconductor substrate 1 has a surface 11. Thesurface 11 faces one side in a thickness direction Z1 of thesemiconductor substrate 1.

The semiconductor substrate 1 includes edges 131-134. The edge 131 andthe edge 133 are spaced apart from each other in a first direction X1.Both of the edge 131 and the edge 133 extend along a second directionX2. The second direction X2 is perpendicular to the first direction X1.The edge 132 and the 134 are spaced apart from each other in the seconddirection X2. Both of the edge 132 and the edge 134 extend along thefirst direction X1. The edge 131 is connected to the edge 132, the edge132 to the edge 133, the edge 133 to the edge 134, and the edge 134 tothe edge 131.

FIG. 4 shows the region IV in FIG. 2 as enlarged. As shown in FIG. 4,the semiconductor substrate 1 is formed with a semiconductor layer 91 a.The semiconductor layer 91 a is made of GaInAs, for example.

The active element 5, which is shown in FIGS. 2 and 4, is formed on thesemiconductor substrate 1. The active element 5 is electricallyconnected to the first conductive layer 2 and the second conductivelayer 3. The active element 5 is formed on the semiconductor layer 91 a.The active element 5 forms a resonator between the second conductivelayer 3 and the first conductive layer 2. The electromagnetic wavesemitted from the active element 5 are reflected by a back-surfacereflective metal layer 88, to have a surface-emission radiation patternperpendicular to the semiconductor substrate 1 (in the thicknessdirection Z1).

A typical example of the active element 5 is an RTD. However, the activeelement 5 may be provided by a diode other than an RTD or a transistor.For example, the active element 5 may be provided by a tunnel transittime (TUNNETT) diode, an impact ionization avalanche transit time(IMPATT) diode, a GaAs-based field effect transistor (FET), a GaN-basedFET, a high electron mobility transistor (HEMT), and a heterojunctionbipolar transistor (HBT).

One implementation of the active element 5 is described below withreference to FIGS. 5 and 6. As shown in these figures, the semiconductorlayer 91 a is disposed on the semiconductor substrate 1. Thesemiconductor layer 91 a may be made of GaInAs as described above anddoped with an n-type impurity at a high concentration. A GaInAs layer 92a is disposed on the GaInAs layer 91 a and doped with an n-typeimpurity. A GaInAs layer 93 a is disposed on the GaInAs layer 92 a andis not doped with any impurity. An AlAs layer 94 a is disposed on theGaInAs layer 93 a, an InGaAs layer 95 on the AlAs layer 94 a, and anAlAs layer 94 b on the InGaAs layer 95. The AlAs layer 94 a, the InGaAslayer 95 and the AlAs layer 94 b provide an RTD part. A GaInAs layer 93b is disposed on the AlAs layer 94 b and is not doped with any impurity.A GaInAs layer 92 b is disposed on the GaInAs layer 93 b and doped withan n-type impurity. A GaInAs layer 91 b is disposed on the GaInAs layer92 b and is doped with an n-type impurity at a high concentration. Thefirst conductive layer 2 is disposed on the GaInAs layer 91 b. Thesecond conductive layer 3 is disposed on the GaInAs layer 91 a.

Though not illustrated, unlike the configuration shown in FIG. 6, aGaInAs layer doped with an n-type impurity at a high concentration maybe interposed between the GaInAs layer 91 b and the first conductivelayer 2. Such a configuration enhances the contact between the firstconductive layer 2 and the GaInAs layer 91 b.

An insulating film such as a SiO₂ film, a Si₃N₄ film, a SiON film, anHfO₂ film, an Al₂O₃ film or a multi-layered film made up of these, forexample, may be deposited on a side wall of the lamination structureshown in FIG. 6.

As shown in FIG. 2, for example, each of the first conductive layer 2and the second conductive layer 3 is formed on the semiconductorsubstrate 1. The first conductive layer 2 and the second conductivelayer 3 are insulated from each other. Each of the first conductivelayer 2 and the second conductive layer 3 has a metal-laminatedstructure. For example, each of the first conductive layer 2 and thesecond conductive layer 3 may be provided by laminating Au, Pd and Ti.Alternatively, each of the first conductive layer 2 and the secondconductive layer 3 may be provided by laminating Au and Ti. Each of thefirst conductive layer 2 and the second conductive layer 3 may beapproximately 20 to 2000 nm in thickness. Each of the first conductivelayer 2 and the second conductive layer 3 may be formed by vacuum vapordeposition or sputtering, for example.

The first conductive layer 2 includes a first antenna part 21, a firstinductance part 22, a first capacitor part 23 and a first conductivepart 25. The second conductive layer 3 includes a second antenna part31, a second inductance part 32, a second capacitor part 33 and a secondconductive part 35.

The first antenna part 21 extends along the first direction X1. Thefirst inductance part 22 is connected to the first antenna part 21 andthe first capacitor part 23 and extends from the first antenna part 21to the first capacitor part 23 along the second direction X2. The firstinductance part 22 functions as an inductance. The length L1 (see FIG.4) of the first inductance part 22 in the second direction X2 is 5 μm to100 μm, for example. The width of the first inductance part 22 is 1 μmto 10 μm, for example. As shown in FIG. 4, as viewed in the thicknessdirection Z1, the first inductance part 22 is spaced apart from thesemiconductor layer 91 a.

The second antenna part 31 extends along the third direction X3. Thethird direction X3 is the direction opposite to the first direction X1.The second inductance part 32 is connected to the second antenna part 31and the second capacitor part 33 and extends from the second antennapart 31 to the second capacitor part 33 along the second direction X2.The second inductance part 32 functions as an inductance. The length L2(see FIG. 4) of the second inductance part 32 in the second direction X2is 5 μm to 100 μm, for example. The width of the second inductance part32 is 1 μm to 10 μm, for example.

The length L1 of the first inductance part 22 in the second direction X2and the length L2 of the second inductance part 32 in the seconddirection X2 may influence the oscillation frequency of the terahertzwaves. In the present embodiment, the oscillation frequency of theterahertz waves is 300 GHz. To realize the oscillation frequency of 300GHz, the length L1 of the first inductance part 22 in the seconddirection X2 and the length L2 of the second inductance part 32 in thesecond direction X2 are set to 10 μm. As shown in FIG. 4, as viewed inthe thickness direction Z1, the second inductance part 32 is spacedapart from the semiconductor layer 91 a.

As shown in e.g. FIGS. 2 and 4, the first capacitor part 23 ispositioned offset from the active element 5 in the second direction X2.In the present embodiment, the first capacitor part 23 is rectangular asviewed in the thickness direction Z1. The first capacitor part 23 has afirst capacitor-part side surface 231 and a second capacitor-part sidesurface 232. The first capacitor-part side surface 231 is the side ofthe first capacitor part 23 in the first direction X1. The firstcapacitor-part side surface 231 extends along the second direction X2.The first capacitor-part side surface 231 is offset in the thirddirection X3, which is opposite to the first direction X1, from the end211 of the first antenna part 21 in the first direction X1. The secondcapacitor-part side surface 232 is the side of the first capacitor part23 in the third direction X3. The second capacitor-part side surface 232extends along the second direction X2. The second capacitor-part sidesurface 232 is offset in the first direction X1 from the end 311 of thesecond antenna part 31 in the third direction X3.

FIG. 3 is a view obtained by omitting the first conductive part 25 andthe first capacitor part 23 from FIG. 2.

The second capacitor part 33 is positioned offset from the activeelement 5 in the second direction X2. As shown in FIG. 15, the firstcapacitor part 23 is interposed between the second capacitor part 33 andthe semiconductor substrate 1. Unlike the present embodiment, the secondcapacitor part 33 may be interposed between the first capacitor part 23and the semiconductor substrate 1. The second capacitor part 33 isstacked over the first capacitor part 23 and insulated from the firstcapacitor part 23 by the insulating layer 4. The second capacitor part33 and the first capacitor part 23 provide a capacitor. In the presentembodiment, the second capacitor part 33 is rectangular as viewed in thethickness direction Z1. In the present embodiment, as shown in FIG. 15,the dimension W2 of the second capacitor part 33 in the first directionX1 differs from the dimension W1 of the first capacitor part 23 in thefirst direction X1. In the present embodiment, the dimension W2 of thesecond capacitor part 33 in the first direction X1 is larger than thedimension W1 of the first capacitor part 23 in the first direction X1.This allows the second capacitor part 33 to be reliably formed above thefirst capacitor part 23 even when the formation position of the secondcapacitor part 33 is deviated due to a manufacturing error. Unlike thepresent embodiment, the dimension W2 of the second capacitor part 33 inthe first direction X1 may be smaller than the dimension W1 of the firstcapacitor part 23 in the first direction X1.

As shown in FIG. 3, the second capacitor part 33 has a firstcapacitor-part side surface 331 and a second capacitor-part side surface332. The first capacitor-part side surface 331 is the side of the secondcapacitor part 33 in the first direction X1. The first capacitor-partside surface 331 extends along the second direction X2. The firstcapacitor-part side surface 331 is offset in the third direction X3,which is opposite to the first direction X1, from the end 211 of thefirst antenna part 21 in the first direction X1. The secondcapacitor-part side surface 332 is the side of the second capacitor part33 in the third direction X3. The second capacitor-part side surface 332extends along the second direction X2. The second capacitor-part sidesurface 332 is offset in the first direction X1 from the end 311 of thesecond antenna part 31 in the third direction X3.

As shown in FIG. 2, the semiconductor substrate 1 includes an exposedpart 12A and an exposed part 12B. The exposed part 12A and the exposedpart 12B are the portions that are exposed from the first capacitor part23 and the second capacitor part 33. The exposed part 12A is positionedoffset from the first capacitor part 23 and the second capacitor part 33in the first direction X1. The exposed part 12B is positioned offsetfrom the first capacitor part 23 and the second capacitor part 33 in thethird direction X3.

The first conductive part 25 is connected to the first capacitor part23. In the present embodiment, the first conductive part 25 isrectangular. In the present embodiment, the first conductive part 25 isa pad portion to which the wire 871 (see FIG. 1) is bonded. As shown inFIG. 11, the first conductive part 25 has a portion that is held indirect contact with the semiconductor substrate 1. As viewed in thethickness direction Z1, this contacting portion overlaps with awire-bonding part where the wire 871 and the first conductive part 25are in contact with each other. As shown in FIG. 2, the first conductivepart 25 has a portion 259 that is spaced apart from the first antennapart 21 in the second direction X2 with the exposed part 12A betweenthem, as viewed in the thickness direction Z1. The first conductive part25 includes a first conductive-part side surface 251. The firstconductive-part side surface 251 is spaced apart from the first antennapart 21 in the second direction X2 with the exposed part 12A betweenthem, as viewed in the thickness direction Z1. In the presentembodiment, the first conductive-part side surface 251 extends along thefirst direction X1. Unlike the present embodiment, the firstconductive-part side surface 251 may be curved.

In the present embodiment, as shown in FIG. 2, the first conductive part25 reaches the edge 131 and the edge 132, as viewed in the thicknessdirection Z1. As shown in FIG. 17, the first conductive part 25 may notreach the edge 131 and the edge 132 as viewed in the thickness directionZ1. Such an arrangement reduces formation of burrs in the process ofmanufacturing the terahertz element B1, which may occur by cutting thefirst conductive part 25 in dicing the semiconductor substrate 1.

The second conductive part 35 is connected to the second capacitor part33. In the present embodiment, the second conductive part 35 isrectangular. In the present embodiment, the second conductive part 35 isa pad portion to which the wire 872 is bonded. As shown in FIG. 12, thesecond conductive part 35 has a portion that is held in direct contactwith the semiconductor substrate 1. As viewed in the thickness directionZ1, this contacting portion overlaps with a wire-bonding part where thewire 872 and the second conductive part 35 are in contact with eachother. As shown in FIG. 2, the second conductive part 35 has a portion359 that is spaced apart from the second antenna part 31 in the seconddirection X2 with the exposed part 12B between them, as viewed in thethickness direction Z1. The second conductive part 35 includes a secondconductive-part side surface 351. The second conductive-part sidesurface 351 is spaced apart from the second antenna part 31 in thesecond direction X2 with the exposed part 12B between them, as viewed inthe thickness direction Z1. In the present embodiment, the secondconductive-part side surface 351 extends along the first direction X1.Unlike the present embodiment, the second conductive-part side surface351 may be curved.

In the present embodiment, as shown in FIG. 2, the second conductivepart 35 reaches the edge 133 and the edge 132, as viewed in thethickness direction Z1. As shown in FIG. 17, the second conductive part35 may not reach the edge 133 and the edge 132 as viewed in thethickness direction Z1. Such an arrangement reduces formation of burrsin the process of manufacturing the terahertz element B1, which mayoccur by cutting the second conductive part 35 in dicing thesemiconductor substrate 1.

The insulating layer 4, which is shown in FIGS. 8-15, is made of SiO₂,for example. Alternatively, the material forming the insulating layer 4may be Si₃N₄, SiON, HfO₂ or Al₂O₃. The insulating layer 4 may beapproximately 10 nm to 1000 nm in thickness. The insulating layer 4 maybe formed by CVD or sputtering, for example. The insulating layer 4 isinterposed between the first conductive layer 2 (e.g. the first antennapart 21, the first inductance part 22 and the first conductive part 25)and the semiconductor substrate 1 and between the second conductivelayer 3 (the second antenna part 31, the second inductance part 32 andthe second conductive part 35) and the semiconductor substrate 1. Asdescribed above, a part of the insulating layer 4 is interposed betweenthe first capacitor part 23 and the second capacitor part 33.

FIG. 16 is a sectional view of the semiconductor device A1 of FIG. 1.

The wiring board 81 shown in FIG. 16 is a glass epoxy board, forexample. The terahertz element B1 is disposed on the wiring board 81.The wiring board 81 is formed with a wiring pattern 82. The wiringpattern 82 includes a first portion 821 and a second portion 822. Thefirst portion 821 and the second portion 822 are spaced apart from eachother.

The insulating part 85 is disposed on the wiring board 81. Theinsulating part 85 may be made of resin (e.g. epoxy resin). Theinsulating part 85 has a surface 853. The surface 853 faces one side inthe thickness direction of the wiring board 81 (which corresponds to thethickness direction Z1 of the semiconductor substrate 1 in the presentembodiment). The insulating part 85 is formed with an opening 851 inwhich the terahertz element B1 is housed. The opening 851 has a firstside surface 851A and a second side surface 851B. The first side surface851A is inclined with respect to the thickness direction Z1 of thewiring board 81. The second side surface 851B is positioned between thefirst side surface 851A and the wiring board 81 in the thicknessdirection Z1 of the wiring board 81. The second side surface 851Bextends along the thickness direction Z1 of the wiring board 81. Thedimension of the second side surface 851B in the thickness direction Z1of the wiring board 81 is larger than the dimension of the terahertzelement B1 in the thickness direction Z1 of the wiring board 81.

As shown in FIG. 16, a metal layer 86 may be formed on the first sidesurface 851A. As shown in the figure, the metal layer 86 may be formedon the second side surface 851B as well. The metal layer 86 may beformed by metal plating. The metal layer 86 efficiently reflectsterahertz waves. The wires 871 and 872 are bonded to the terahertzelement B1 and the wiring board 81 (more specifically, the wiringpattern 82). The wire 871 is bonded to the first conductive part 25 ofthe terahertz element B1 and the first portion 821 of the wiring pattern82. The wire 872 is bonded to the second conductive part 35 of theterahertz element B1 and the second portion 822 of the wiring pattern82. The first side surface 851A and the second side surface 851B may bemade of metal.

In the present embodiment, as shown in FIG. 2, the semiconductorsubstrate 1 includes the exposed part 12A exposed from the firstcapacitor part 23 and the second capacitor part 33. The first conductivepart 25 has the portion 259 that is spaced apart from the first antennapart 21 in the second direction X2 with the exposed part 12A betweenthem, as viewed in the thickness direction Z1. Such an arrangementreduces the area of the first conductive layer 2 that is close to theactive element 5. This reduces the possibility that the first conductivelayer 2 (the first conductive part 25, in particular) adversely affectsthe polarization characteristics of the terahertz waves emitted from theactive element 5.

In the present embodiment, as shown in FIG. 11, the first conductivepart 25 has a portion that is held in direct contact with thesemiconductor substrate 1. Such an arrangement allows for bonding a wireto a relatively hard portion of the first conductive part 25. Thisprevents detachment of the wire from the first conductive part 25. Thesecond conductive part 35 shown in FIG. 12 has the same advantage.

In the present embodiment, the opening 851 of the insulating part 85 hasthe first side surface 851A, as shown in FIG. 16. The first side surface851A is inclined with respect to the thickness direction Z1 of thewiring board 81. With such an arrangement, even when terahertz wavesemitted from the terahertz element B1 are reflected back by a terahertzwave detection device and reflected on the first side surface 851A, suchreflected waves can be prevented from traveling toward the detectiondevice. This reduces interference due to the reflection of terahertzwaves. At the same time, the antenna efficiency is improved.

In the present embodiment, as shown in FIG. 16, the second side surface851B extends along the thickness direction Z1 of the wiring board 81.With such an arrangement, terahertz waves can be reflected on the secondside surface 851B a plurality of times so as to travel in the thicknessdirection Z1. Thus, the terahertz waves are efficiently directed upwardin FIG. 16.

In the present embodiment, the dimension of the second side surface 851Bin the thickness direction Z1 of the wiring board 81 is larger than thedimension of the terahertz element B1 in the thickness direction Z1 ofthe wiring board 81. With such an arrangement, the terahertz waves aremore efficiently directed upward in FIG. 16.

Second Embodiment

A second embodiment of the present disclosure is described below withreference to FIG. 18.

In the following descriptions, the structures that are identical orsimilar to the above are denoted by the same reference signs as above,and descriptions thereof are omitted appropriately.

In the terahertz element B2 shown in FIG. 18, the first conductive part25 includes a first conductive section 253 and a first extension 254extending out of the first conductive section 253. The first extension254 is connected to the first capacitor part 23. The second conductivepart 35 includes a second conductive section 353 and a second extension354 extending out of the second conductive section 353. The secondextension 354 is connected to the second capacitor part 33. Since otherpoints of the terahertz element B2 are generally the same as thosedescribed above as to the terahertz element B1, the description isomitted. The present embodiment provides the same advantages as thosedescribed above as to the first embodiment.

Third Embodiment

A third embodiment of the present disclosure is described below withreference to FIG. 19.

The terahertz element B3 shown in FIG. 19 differs from the terahertzelement B1 in shape of the first conductive layer 2 and the secondconductive layer 3. In the terahertz element B3, the second conductivelayer 3 includes a second conductive part 35 disposed opposite to thefirst conductive part 25 with the active element 5 between them.

The first conductive layer 2 includes a third inductance part 236 and athird capacitor part 237, in addition to the first antenna part 21, thefirst inductance part 22, the first capacitor part 23 and the firstconductive part 25. The second conductive layer 3 includes a fourthinductance part 336 and a fourth capacitor part 337, in addition to thesecond antenna part 31, the second inductance part 32, the secondcapacitor part 33 and the second conductive part 35.

The first antenna part 21 extends along the first direction X1. Thefirst inductance part 22 is connected to the first antenna part 21 andthe first capacitor part 23 and extends from the first antenna part 21to the first capacitor part 23 along the second direction X2. The thirdinductance part 236 is connected to the first antenna part 21 and thethird capacitor part 237 and extends from the third capacitor part 237to the first antenna part 21 along the second direction X2. The firstinductance part 22 and the third inductance part 236 function as aninductance.

The length of each of the first inductance part 22 and the thirdinductance part 236 in the second direction X2 is 10 μm to 200 μm, forexample. The width of each of the first inductance part 22 and the thirdinductance part 236 is 1 μm to 10 μm, for example. To obtain the sameoscillation frequency as the terahertz element B1 of the firstembodiment, the length in the second direction X2 of each of the firstinductance part 22 and the third inductance part 236 of the presentembodiment may be set to twice the length in the second direction X2 ofthe first inductance part 22 of the first embodiment.

The second antenna part 31 extends along the third direction X3. Thesecond inductance part 32 is connected to the second antenna part 31 andthe second capacitor part 33 and extends from the second antenna part 31to the second capacitor part 33 along the second direction X2. Thefourth inductance part 336 is connected to the second antenna part 31and the fourth capacitor part 337 and extends from the fourth capacitorpart 337 to the second antenna part 31 along the second direction X2.The second inductance part 32 and the fourth inductance part 336function as an inductance.

The length of each of the second inductance part 32 and the fourthinductance part 336 in the second direction X2 is 10 μm to 200 μm, forexample. The width of each of the second inductance part 32 and thefourth inductance part 336 is 1 μm to 10 μm, for example. To obtain thesame oscillation frequency as the terahertz element B1 of the firstembodiment, the length in the second direction X2 of each of the secondinductance part 32 and the fourth inductance part 336 of the presentembodiment may be set to twice the length in the second direction X2 ofthe second inductance part 32 of the first embodiment.

The first capacitor part 23 and the second capacitor part 33 are notdescribed herein, because the description given above as to the firstembodiment is applicable.

The semiconductor substrate 1 includes an exposed part 12A, an exposedpart 12B, an exposed part 12C and an exposed part 12D. Since the exposedpart 12A and the exposed part 12B are as described above in the firstembodiment, description in the present embodiment is omitted. Theexposed part 12C and the exposed part 12D are the portions exposed fromthe third capacitor part 237 and the fourth capacitor part 337. Theexposed part 12C is positioned offset from the third capacitor part 237and the fourth capacitor part 337 in the first direction X1. The exposedpart 12D is positioned offset from the third capacitor part 237 and thefourth capacitor part 337 in the third direction X3.

The first conductive part 25 is connected to the first capacitor part23. The entirety of the first capacitor part 23 overlaps with the firstconductive part 25 in the first direction X1. In the present embodiment,the first conductive part 25 is rectangular. In the present embodiment,the first conductive part 25 is a conductive portion to which a wire isbonded. The first conductive part 25 has a portion 259A that is spacedapart from the first antenna part 21 in the second direction X2 with theexposed part 12A between them, as viewed in the thickness direction Z1.The first conductive part 25 has a portion 259B that is spaced apartfrom the second antenna part 31 in the second direction X2 with theexposed part 12B between them, as viewed in the thickness direction Z1.

The second conductive part 35 is connected to the fourth capacitor part337. The entirety of the fourth capacitor part 337 overlaps with thesecond conductive part 35 in the first direct ion X1. In the presentembodiment, the second conductive part 35 is rectangular. In the presentembodiment, the second conductive part 35 is a conductive portion towhich a wire is bonded. The second conductive part 35 has a portion 359Athat is spaced apart from the first antenna part 21 in the fourthdirection X4, which is opposite to the second direction X2, with theexposed part 12C between them, as viewed in the thickness direction Z1.The second conductive part 35 has a portion 359B that is spaced apartfrom the second antenna part 31 in the fourth direction X4 with theexposed part 12B between them, as viewed in the thickness direction Z1.

The present embodiment provides the same advantages as those describedabove as to the first embodiment.

Fourth Embodiment

A fourth embodiment of the present disclosure is described below withreference to FIG. 20.

In the terahertz element B4 shown in the figure, the first conductivelayer 2 has a portion 29, and the second conductive layer 3 has aportion 39. In the present embodiment, the portion 29 and the portion 39may be stacked over each other while being insulated from each other.The present embodiment provides the same advantages as those describedabove as to the first embodiment.

EXAMPLES

Examples of the first embodiment of the present disclosure are describedbelow with reference to FIGS. 21-25. The examples of the firstembodiment described below are applicable to the embodiments other thanthe first embodiment (i.e., the second, the third and the fourthembodiments).

As shown in FIGS. 21 and 22, the dimension of one side of thesemiconductor device A1 as viewed in plan is defined as dimension L11,the dimension of the other side is defined as dimension L12, and theinner diameter of the opening 851 is defined as inner diameter D1. Asshown in FIG. 22, the dimension of first side surface 851A of theopening 851 in the direction Z1 is defined as dimension L22, and thedimension of the second side surface 851B of the opening 851 in thedirection Z1 is defined as dimension L21. FIG. 21 and FIG. 22 are theviews corresponding to FIG. 1 and FIG. 16, respectively, to whichindications of dimensions and inner diameters are added.

FIG. 23 shows the antenna gain (Gain) versus frequencies of terahertzwaves from the semiconductor device A1 for different inner diameters D1.FIG. 23 shows the calculation results in the cases where the innerdiameter D1 is 1.8 mm, 2.0 mm and 2.2 mm. Note that each of thedimensions L11 and L12 is set to 3.4 mm, the dimension L21 to 0.9 mm,and the dimension L22 to 1.0 mm. The first side surface 851A of theopening 851 is inclined 20 degrees with respect to the direction Z1. Itis preferable that the antenna gain of the semiconductor device A1 isnot less than 7 dB or 8 dB, for example. In the example shown in FIG.23, the semiconductor device A1 exhibits the antenna gain of not lessthan 7 dB, for example, in any of the cases where the inner diameter D1is 1.8 mm, 2.0 mm and 2.2 mm. For example, preferable results areexhibited when the frequency of the terahertz element is in the range of300 to 330 GHz. However, frequencies of the terahertz element other thanthis range may be used. According to FIG. 23, the inner diameter D1 maybe set to 1.7 to 1.9 mm, for example, in light of the results in thecase where the inner diameter D1 is 1.8 mm. According to FIG. 23, theinner diameter D1 may be set to 1.9 to 2.1 mm, for example, in light ofthe results in the case where the inner diameter D1 is 2.0 mm. Accordingto FIG. 23, the inner diameter D1 may be set to 2.1 to 2.3 mm, forexample, in light of the results in the case where the inner diameter D1is 2.2 mm. Also, the inner diameter D1 may be set to 1.7 to 2.3 mm.

FIG. 24 shows the antenna gain (Gain) versus frequencies of terahertzwaves from the semiconductor device A1 for different dimensions L21.FIG. 24 shows the calculation results in the cases where the dimensionL21 is 0.3 mm, 0.6 mm and 0.9 mm. In the example shown in FIG. 24, thedimension L21 is made relatively large to improve the performance of thesemiconductor device A1. Note that the dimensions L11 and L12 each are3.4 mm, the inner diameter D1 is 2.2 mm, and the dimension L22 is 1.0mm. The first side surface 851A of the opening 851 is inclined 20degrees with respect to the direction Z1. It is preferable that theantenna gain of the semiconductor device A1 is not less than 7 dB or 8dB, for example. In the example shown in FIG. 24, the semiconductordevice A1 exhibits the antenna gain of not less than 7 dB, for example,in any of the cases where the dimension L21 is 0.3 mm, 0.6 mm and 0.9mm. For example, preferable results are exhibited when the frequency ofthe terahertz element is in the range of 300 to 330 GHz. However,frequencies of the terahertz element other than this range may be used.According to FIG. 24, the dimension L21 may be set to 0.2 to 0.4 mm, forexample, in light of the results in the case where the dimension L21 is0.3 mm. According to FIG. 24, the dimension L21 may be set to 0.5 to 0.7mm, for example, in light of the results in the case where the dimensionL21 is 0.6 mm. According to FIG. 24, the dimension L21 may be set to 0.8to 1.0 mm, for example, in light of the results in the case where thedimension L21 is 0.9 mm. Also, the dimension L21 may be set to 0.2 to1.0 mm.

FIG. 25 shows the antenna gain (Gain) versus frequencies of terahertzwaves from the semiconductor device A1 for different dimensions L22.FIG. 25 shows the calculation results in the cases where the dimensionL22 is 0.7 mm, 1.0 mm and 1.3 mm. In the example shown in FIG. 25, thedimension L22 is made relatively large to improve the performance of thesemiconductor device A1. Note that the dimensions L11 and L12 each are3.4 mm, the inner diameter D1 is 2.2 mm, and the dimension L21 is 0.9mm. The first side surface 851A of the opening 851 is inclined 20degrees with respect to the direction Z1. It is preferable that theantenna gain of the semiconductor device A1 is not less than 7 dB or 8dB, for example. In the example shown in FIG. 25, the semiconductordevice A1 exhibits the antenna gain of not less than 7 dB, for example,in any of the cases where the dimension L22 is 0.7 mm, 1.0 mm and 1.3mm. For example, preferable results are exhibited when the frequency ofthe terahertz element is in the range of 300 to 330 GHz. However,frequencies of the terahertz element other than this range may be used.According to FIG. 25, the dimension L22 may be set to 0.6 to 0.8 mm, forexample, in light of the results in the case where the dimension L22 is0.7 mm. According to FIG. 25, the dimension L22 may be set to 0.9 to 1.1mm, for example, in light of the results in the case where the dimensionL22 is 1.0 mm. According to FIG. 25, the dimension L22 may be set to 1.2to 1.4 mm, for example, in light of the results in the case where thedimension L22 is 1.3 mm. Also, the dimension L22 may be set to 0.6 to1.4 mm.

The present disclosure is not limited to the foregoing embodiments. Thespecific configuration of each part of the present disclosure may bevaried in many ways.

The above-described embodiments include the following clauses.

Clause 1.

A terahertz element comprising:

a semiconductor substrate;

a first conductive layer and a second conductive layer each formed onthe semiconductor substrate and insulated from each other; and

an active element formed on the semiconductor substrate and electricallyconnected to the first conductive layer and the second conductive layer,wherein

the first conductive layer includes a first antenna part extending alonga first direction, a first capacitor part positioned offset from theactive element in a second direction as viewed in a thickness directionof the semiconductor substrate, and a first conductive part connected tothe first capacitor part, the second direction being perpendicular tothe thickness direction and the first direction,

the second conductive layer includes a second capacitor part, the secondcapacitor part being stacked over the first capacitor part while beinginsulated from the first capacitor part,

the semiconductor substrate includes an exposed part that is exposedfrom the first capacitor part and the second capacitor part, and

the first conductive part has a portion that is spaced apart from thefirst antenna part in the second direction with the exposed parttherebetween as viewed in the thickness direction.

Clause 2.

The terahertz element according to clause 1, wherein the secondconductive layer includes a second antenna part extending along a thirddirection that is opposite to the first direction.

Clause 3.

The terahertz element according to clause 2, wherein the firstconductive layer includes a first inductance part, the first inductancepart being connected to the first antenna part and the first capacitorpart while extending from the first antenna part to the first capacitorpart along the second direction, and

the second conductive layer includes a second inductance part, thesecond inductance part being connected to the second antenna part andthe second capacitor part while extending from the second antenna partto the second capacitor part along the second direction.

Clause 4.

The terahertz element according to clause 2 or 3, wherein the firstcapacitor part has a first capacitor-part side surface that is a side ofthe first capacitor part in the first direction,

the first capacitor-part side surface of the first capacitor part isoffset in the third direction from an end of the first antenna part inthe first direction,

the second capacitor part has a first capacitor-part side surface thatis on a side of the second capacitor part in the first direction, and

the first capacitor-part side surface of the second capacitor part isoffset in the third direction from the end of the first antenna part inthe first direction.

Clause 5.

The terahertz element according to clause 4, wherein the first capacitorpart has a second capacitor-part side surface that is on a side of thefirst capacitor part in the third direction,

the second capacitor-part side surface of the first capacitor part isoffset in the first direction from an end of the second antenna part inthe third direction,

the second capacitor part has a second capacitor-part side surface thatis on a side of the second capacitor part in the third direction, andthe second capacitor-part side surface of the second capacitor part isoffset in the first direction from the end of the second antenna part inthe third direction.

Clause 6.

The terahertz element according to any of clauses 1-5, wherein the firstcapacitor part has a dimension in the first direction that is differentfrom a dimension of the second capacitor part in the second direction.

Clause 7.

The terahertz element according to any of clauses 1-6, wherein the firstconductive part has a first conductive-part side surface that is spacedapart from the first antenna part in the second direction, and

the first conductive-part side surface extends along the firstdirection.

Clause 8.

The terahertz element according to any of clauses 1-7, wherein the firstconductive part has a portion held in direct contact with thesemiconductor substrate.

Clause 9.

The terahertz element according to any of clauses 1-8, wherein thesecond conductive layer includes a second conductive part connected tothe second capacitor part, and

the first conductive part is spaced apart from the second conductivepart in the first direction.

Clause 10.

The terahertz element according to clause 1, wherein the firstconductive part includes a first conductive section and a firstextension extending out of the first conductive section,

the first extension is connected to the first capacitor part,

the second conductive part includes a second conductive section and asecond extension extending out of the second conductive section, and

the second extension is connected to the second capacitor part.

Clause 11.

The terahertz element according to clause 3, wherein the secondconductive layer includes a second conductive part disposed opposite tothe first conductive part with the active element therebetween.

Clause 12.

The terahertz element according to clause 11, wherein an entirety of thefirst capacitor part overlaps with the first conductive part in thefirst direction.

Clause 13.

The terahertz element according to clause 11 or 12, wherein the firstconductive layer includes a third capacitor part and a third inductancepart,

the third capacitor part is positioned opposite to the first capacitorpart with the first antenna part therebetween,

the third inductance part is connected to the first antenna part and thethird capacitor part while extending from the third capacitor part tothe first antenna part along the second direction,

the second conductive layer includes a fourth capacitor part and afourth inductance part,

the fourth capacitor part is positioned opposite to the second capacitorpart with the second antenna part therebetween, and

the fourth inductance part is connected to the second antenna part andthe fourth capacitor part while extending from the fourth capacitor partto the second antenna part along the second direction.

Clause 14.

The terahertz element according to clause 1, further comprising aninsulating layer interposed between the semiconductor substrate and eachof the first conductive layer and the second conductive layer.

Clause 15.

The terahertz element according to clause 14, wherein a part of theinsulating layer is interposed between the first capacitor part and thesecond capacitor part.

Clause 16.

A semiconductor device comprising:

a support;

a terahertz element as set forth in clause 1, the terahertz elementbeing disposed on the support; and

an insulating part disposed on the support, wherein

the insulating part is formed with an opening in which the terahertzelement is housed, and

the opening has a first side surface, the first side surface beinginclined with respect to a thickness direction of the support.

Clause 17.

The semiconductor device according to clause 16, wherein the opening hasa second side surface surrounding the terahertz element, the second sidesurface being positioned between the first side surface and the supportin the thickness direction of the support, and

the second side surface extends along the thickness direction of thesupport.

Clause 18.

The semiconductor device according to clause 17, wherein the second sidesurface has a dimension in the thickness direction of the support thatis larger than a dimension of the terahertz element in the thicknessdirection of the support.

Clause 19.

The semiconductor device according to clause 17 or 18, furthercomprising a metal layer formed on the first side surface.

Clause 20.

The semiconductor device according to any of clauses 16-19, furthercomprising a wire bonded to the terahertz element and the support.

1. A terahertz element comprising: a semiconductor substrate; a firstconductive layer and a second conductive layer each formed on thesemiconductor substrate and insulated from each other; and an activeelement formed on the semiconductor substrate and electrically connectedto the first conductive layer and the second conductive layer, whereinthe first conductive layer includes a first antenna part extending alonga first direction, a first capacitor part positioned offset from theactive element in a second direction as viewed in a thickness directionof the semiconductor substrate, and a first conductive part connected tothe first capacitor part, the second direction being perpendicular tothe thickness direction and the first direction, the second conductivelayer includes a second capacitor part, the second capacitor part beingstacked over the first capacitor part while being insulated from thefirst capacitor part, the semiconductor substrate includes an exposedpart that is exposed from the first capacitor part and the secondcapacitor part, and the first conductive part has a portion that isspaced apart from the first antenna part in the second direction withthe exposed part therebetween as viewed in the thickness direction. 2.The terahertz element according to claim 1, wherein the secondconductive layer includes a second antenna part extending along a thirddirection that is opposite to the first direction.
 3. The terahertzelement according to claim 2, wherein the first conductive layerincludes a first inductance part, the first inductance part beingconnected to the first antenna part and the first capacitor part whileextending from the first antenna part to the first capacitor part alongthe second direction, and the second conductive layer includes a secondinductance part, the second inductance part being connected to thesecond antenna part and the second capacitor part while extending fromthe second antenna part to the second capacitor part along the seconddirection.
 4. The terahertz element according to claim 2 or 3, whereinthe first capacitor part has a first capacitor-part side surface that isa side of the first capacitor part in the first direction, the firstcapacitor-part side surface of the first capacitor part is offset in thethird direction from an end of the first antenna part in the firstdirection, the second capacitor part has a first capacitor-part sidesurface that is on a side of the second capacitor part in the firstdirection, and the first capacitor-part side surface of the secondcapacitor part is offset in the third direction from the end of thefirst antenna part in the first direction.
 5. The terahertz elementaccording to claim 4, wherein the first capacitor part has a secondcapacitor-part side surface that is on a side of the first capacitorpart in the third direction, the second capacitor-part side surface ofthe first capacitor part is offset in the first direction from an end ofthe second antenna part in the third direction, the second capacitorpart has a second capacitor-part side surface that is on a side of thesecond capacitor part in the third direction, and the secondcapacitor-part side surface of the second capacitor part is offset inthe first direction from the end of the second antenna part in the thirddirection.
 6. The terahertz element according to claim 1, wherein thefirst capacitor part has a dimension in the first direction that isdifferent from a dimension of the second capacitor part in the seconddirection.
 7. The terahertz element according to claim 1, wherein thefirst conductive part has a first conductive-part side surface that isspaced apart from the first antenna part in the second direction, andthe first conductive-part side surface extends along the firstdirection.
 8. The terahertz element according to claim 1, wherein thefirst conductive part has a portion held in direct contact with thesemiconductor substrate.
 9. The terahertz element according to claim 1,wherein the second conductive layer includes a second conductive partconnected to the second capacitor part, and the first conductive part isspaced apart from the second conductive part in the first direction. 10.The terahertz element according to claim 1, wherein the first conductivepart includes a first conductive section and a first extension extendingout of the first conductive section, the first extension is connected tothe first capacitor part, the second conductive part includes a secondconductive section and a second extension extending out of the secondconductive section, and the second extension is connected to the secondcapacitor part.
 11. The terahertz element according to claim 3, whereinthe second conductive layer includes a second conductive part disposedopposite to the first conductive part with the active elementtherebetween.
 12. The terahertz element according to claim 11, whereinan entirety of the first capacitor part overlaps with the firstconductive part in the first direction.
 13. The terahertz elementaccording to claim 11, wherein the first conductive layer includes athird capacitor part and a third inductance part, the third capacitorpart is positioned opposite to the first capacitor part with the firstantenna part therebetween, the third inductance part is connected to thefirst antenna part and the third capacitor part while extending from thethird capacitor part to the first antenna part along the seconddirection, the second conductive layer includes a fourth capacitor partand a fourth inductance part, the fourth capacitor part is positionedopposite to the second capacitor part with the second antenna parttherebetween, and the fourth inductance part is connected to the secondantenna part and the fourth capacitor part while extending from thefourth capacitor part to the second antenna part along the seconddirection.
 14. The terahertz element according to claim 1, furthercomprising an insulating layer interposed between the semiconductorsubstrate and each of the first conductive layer and the secondconductive layer.
 15. The terahertz element according to claim 14,wherein a part of the insulating layer is interposed between the firstcapacitor part and the second capacitor part.
 16. A semiconductor devicecomprising: a support; a terahertz element as set forth in claim 1, theterahertz element being disposed on the support; and an insulating partdisposed on the support, wherein the insulating part is formed with anopening in which the terahertz element is housed, and the opening has afirst side surface, the first side surface being inclined with respectto a thickness direction of the support.
 17. The semiconductor deviceaccording to claim 16, wherein the opening has a second side surfacesurrounding the terahertz element, the second side surface beingpositioned between the first side surface and the support in thethickness direction of the support, and the second side surface extendsalong the thickness direction of the support.
 18. The semiconductordevice according to claim 17, wherein the second side surface has adimension in the thickness direction of the support that is larger thana dimension of the terahertz element in the thickness direction of thesupport.
 19. The semiconductor device according to claim 17, furthercomprising a metal layer formed on the first side surface.
 20. Thesemiconductor device according to claim 16, further comprising a wirebonded to the terahertz element and the support.